Integrated micro-optics for neutral atom quantum processing and photon beam shaping

Fiber-based microcavities are expected to play a crucial role on the way towards scaling and interconnection of neutral-atom quantum processors [1]. Here, we report the fabrication and optical characterization of high-fidelity fiber- and substrate-based micro-concave structures created using focused-ion beam (FIB) milling. We characterize the sphericity of the produced structures and find very high surface precision, on the level of 10 nm. In addition, we present advances in the fabrication of photon beam-shaping elements for the controlled generation of orbital angular momentum (OAM) modes, enabling tailored photonic interfaces for neutral-atom qubits. Developments in high-reflectance optical coatings and their impact on cavity finesse and efficient atom–photon interactions will also be discussed. These advances can open pathways towards fault-tolerant and modular neutral-atom quantum computing.

[1] B. Grinkemeyer et al., “Error-detected quantum operations with neutral atoms mediated by an optical cavity,” Science 387, 1301–1305 (2025).